T. Davis, P. Davies, and C. Lineweaver. (2003)cite arxiv:astro-ph/0305121Comment: 14 pages, including 6 figures, to appear in Classical and Quantum Gravity, reference added.
W. Kinney, and K. Tzirakis. (2007)cite arxiv:0712.2043
Comment: 10 pages, LaTeX; V2: version submitted to PRD. References added,
minor error in text corrected.
D. Lyth, and Y. Rodriguez. (2005)cite arxiv:astro-ph/0502578
Comment: Latex file in Revtex style. 13 pages, 1 figure. v2: minor changes.
Discussion in Subsection VI-A enlarged. References added. Conclusions
unchanged. v3: minor typographic changes. Correlated and uncorrelated \chi^2
non-gaussianity concepts and consequences introduced. Section VI-A enlarged.
Small change in Table I. References updated and added. Conclusions unchanged.
Version to appear in Physical Review D.